Answer:
She buy <u>0.5 pounds</u> of black olives and <u>3.5 pounds</u> of green olives.
Step-by-step explanation:
Given:
Susan is buying black and green olives from the Olive bar for her party. She buys 4 pounds of olives.
Black olives cost three dollars a pound. Green olives cost five dollars a pound.
She spends $15.50.
Now, to find the pounds of olives she buy.
Let the pounds of black olives be ![x.](https://tex.z-dn.net/?f=x.)
And the pounds of green olives be ![y.](https://tex.z-dn.net/?f=y.)
So, total pounds of olives:
![x+y=4](https://tex.z-dn.net/?f=x%2By%3D4)
........( 1 )
As, given the cost of black olives $3 a pound.
And cost of green olives $4 a pound.
Now, the total money spends:
![3x+4y=15.50](https://tex.z-dn.net/?f=3x%2B4y%3D15.50)
Substituting the value of
from equation (1) we get:
![3(4-y)+4y=15.50](https://tex.z-dn.net/?f=3%284-y%29%2B4y%3D15.50)
![12-3y+4y=15.50](https://tex.z-dn.net/?f=12-3y%2B4y%3D15.50)
![12+y=15.50](https://tex.z-dn.net/?f=12%2By%3D15.50)
<em>Subtracting both sides by 12 we get:</em>
![y=3.5](https://tex.z-dn.net/?f=y%3D3.5)
<u>The green olives = 3.5 pounds.</u>
Now, substituting the value of
in equation (1):
![x=4-y\\x=4-3.5\\x=0.5\ pounds.](https://tex.z-dn.net/?f=x%3D4-y%5C%5Cx%3D4-3.5%5C%5Cx%3D0.5%5C%20pounds.)
<u>The black olives = 0.5 pounds.</u>
Therefore, she buy 0.5 pounds of black olives and 3.5 pounds of green olives.